Because Dark-type energy at the time also provided a passive plus 10 damage buff to attacks, Sneasel could easily hit for one-shot knockouts against any target
Vanquisher's Banner and Icon of Ancestry work like this, giving all your Goblins +1/+1, but the more Goblin lords you control, the more of a threat your swarm of 1/1 creeps will be
Thats because she deals 1 point of Willpower damage to each opposing character when shes played
So you can hypothetically evolve your Shiftry so many times -- I don't know, maybe realistically 10 times or something crazy -- and you flip so many coins, and if you hit heads on two or three of them, then you win the game by shuffling in all your opponent's Pokemon
Being an Azorius or Esper deck also means that Affinity will have access to top-tier interaction, the lack of which is the number one reason most fun-looking decks like this fail